1. Field of the Invention
This invention pertains generally to pitless well construction, and more particularly to pitless adapter apparatus for providing a sealed connection between a well drop pipe and a delivery pipe through an opening in the well casing.
2. Related Art
A typical form of well, or booster station, construction employs a tubular well casing that extends vertically downward from the surface of the earth. Lateral distribution from the well may be provided by an underground line below the frost level for the particular area. A spool, also known as a pitless adaptor, provides a connecting device between the well casing and the surface, provides seals for the line from the well to the lateral distribution line, and provides the sealed joint for the pump actuator or the pump motor electric lines.
In pitless well construction, the well drop pipe which supports the pump at the bottom thereof is connected through a coupling or adaptor to a generally horizontally disposed delivery pipe which delivers the well tally disposed delivery pipe which delivers the well water to its point of use. The delivery pipe is generally connected and sealed to the well casing, and the drop pipe is coupled by various types of apparatus to the well casing to be in communication with the delivery pipe. Because of the limited working space within the well casing, various pitless coupling apparatus have been developed wherein a first coupling member is inserted into the opening in the well casing and is rigidly mounted thereto, with the delivery pipe being attached to this first coupling member. A second coupling member, which is attached to the well drop pipe to receive water therefrom, is then passed down into the well casing to slip onto the first coupling member until the two coupling members have their interior bores in communication such that water may be passed therethrough. Because the two coupling members in such coupling schemes are not threaded to each other, a possibility of leakage is presented at the joint between the two coupling members. The releasable fitting between the two coupling members sometimes allows for play in the joint between the members when a pressure moment is applied to the joint. Such moments result from pressure heads within the pressurized well system, are sometimes increased by the turning on off of the pump at the end of the drop pipe, with consequent leakage of water under pressure around the joint and eventual accelerated deterioration of the seal at the joints.
Generally, it is desirable that the coupling member to which the drop pipe is attached be readily removable from the well casing to allow servicing of the coupling and of the drop pipe and pump. In addition, the adapter couplings must be capable of supporting the weight of the pump and drop pipe, and of supporting such weight structurally over a period of time while subject to vibrations and pressure moment stresses.
Examples of pitless adaptors include U.S. Pat. No. 3,482,522 to Fletcher et al.; U.S. Pat. No. 4,037,654 to Lien; U.S. Pat. No. 4,940,087 to Lien et al.; and U.S. Pat. No. 5,669,442 to Gibson, each of which is incorporated herein by reference in its entirety.